Spring! Hello Flowering Ornamentals, Dandelions Pounce, Yellow Patch, and Blue Coat Univ?
We are now in full spring mode. You can tell as many of the usual early spring flowering ornamentals have achieved full bloom — trees of Amelanchier, bradford pear, Forsythia and Magnolia. Next on deck? Late spring things like tulips and Viburnums have begun to flower — V. carlesii or Korean Spice knocked me over this week. If I sound excited, you’d be right. But I digress. We have passed the threshold of cold freezing nighttime temperatures which have been holding growing season 2025 back. It happens every spring. The shoulder seasons of the upper Midwest can be downright frustrating, just ask your favorite grower of landscape woody ornamentals, or herbaceous vegetables, or creeping bentgrass greens. Forecasted high temperatures the end of April are looking balmy (80s for highs) and that’s a good thing. Next week will allow for uninterrupted progression of plant and turf development. Also, northern Illinois low temps look promising — take home message no freezing is forecasted!
Research has begun — Since early March, we have been closely monitoring annual bluegrass (ABW) development at two golf courses in Chicago’s north suburbs. Disease has begun — Our first report of a significant turf disease outbreak came mid-April from a superintendent establishing new creeping bentgrass greens and as he pulled the green covers off, the patches were impressive! Other than that, things have been quieter than normal and that’s a good thing. Notwithstanding many layers of jackets for turfgrass maintenance team members, spring 2025 has allowed for golf course preparations to occur without a hitch? We continue to monitor the development of spring plant phenology, soil temperature (we just crossed 55 degrees), and degree day models to fine turn 1st preventative applications for pest management. For example prevention of take-all patch (common root rot of creeping bentgrass) and fairy ring (hydrophobic soil/thatch disorder of greens) is now on the minds of many a super. Enjoy! P. S. The game of golf can now begin to ramp up to “full swing”.
Weather
Growth Potential Values for Warm Season and Cool Season Turf
One way of looking at turfgrass growth is by calculating the obvious. Both warm season or C4 (bermudagrass and zoysiagrass) and cool season or C3 (bentgrasses, bluegrasses, fescues, ryegrasses) turfgrasses are going to have a minimum as well as an optimum temperature for growth.
Below Cool Season Turfgrass Growth Potential. Below the minimum temperature needed you won’t see much growth for either cool- or warm-season turfgrass = what Chicago just experienced in April.
Above Cool Season Turfgrass Growth Potential. Above optimal temperatures (midsummer) you may see a reduction in growth for cool-season turfgrass = like July in Wichita, Kansas (where I grew up).
Scouting for Disease — Yellow Patch, Rhizoctonia cerealis
A cool temperature Rhizoctonia disease (R. cerealis) reared its ugly head about a week two weeks ago. It is one of our first diseases of the season we will see on golf course greens. Common on brand new greens in Chicago.
Conditions
Air temperatures of 50–65 F with long periods of leaf wetness.
New Bentgrass Greens Most Susceptible
In Chicago, yellow patch can be problematic on newly seeded creeping bentgrass greens. The thinking is that the microbes which are antagonistic are not yet established in the root zone and so why brand new greens are more susceptible. More research is needed on disease suppressive soils.
Disease Suppressive Soils
Research conducted by Dr. Ming-Yi Chou (Rutgers University) showed disease suppressive soils were able to help reduce dollar spot disease of turfgrass in golf course settings.
Disease-suppressive soils have been documented in many economically important crops, but not in turfgrass, one of the most intensively managed plant systems in the United States. Dollar spot, caused by the fungus Clarireedia jacksonii, is the most economically important disease of managed turfgrass and has historically been controlled through the intensive use of fungicides. However, previous anecdotal observations of lower dollar spot severity on golf courses with less intensive fungicide histories suggest that intensive fungicide usage may suppress microbial antagonism of pathogen activity. This study explored the suppressive activity of transplanted microbiomes against dollar spot from seven locations in the Midwestern U.S. and seven locations in the Northeastern U.S. with varying fungicide use histories.
Reference
Chou et al. 2025. Fungicide use intensity influences the soil microbiome and links to fungal disease suppressiveness in amenity turfgrass. Applied and Environmental Microbiology, 91(3).
Blue Coat University — Turfgrass Program
The intent of the Blue Coat University is to educate new board members. The turfgrass program at the Chicago District Golf Association is unique in that it exists as well as has enjoyed broad support by the Executive Director and Board of Directors since it’s inception in 1985. We recently provided training which covered four important aspects. Here’s a slide from each section.
History
Diagnostics
Research
Education & Communication
Final Photo
“Viburnum carlesii, the arrowwood or Korean spice viburnum, is a species of flowering plant in the family Adoxaceae (formerly Caprifoliaceae), native to Korea and Japan (Tsushima Island) and naturalised in USA. Growing to 7 ft tall and broad, it is a bushy deciduous shrub with oval leaves which are copper-coloured when young. Round clusters of red buds open to strongly scented, pale pink flowers in late spring. These are followed in late summer by oval red fruits ripening to black in autumn.” see Wikipedia
